The Igeldamms car park in the capital of Sweden seems like an ordinary underground parking, hewn into the rockface — but it doubles up as a public shelter for 1,200 people in case of a full-scale war.

With tensions with Russia increasing since its so-called military campaign in Ukraine, the Swedish government has pledged to increase sevenfold the budget allocated to civil defense.

Since last year, it has set aside 100 million Swedish kronor annually (around $9 million) to upgrade the 64,000 shelters built during World War Two and the Cold War, to increase its ability to protect the civilian population.

Priority has been given to the modernizing of several dozen large shelters able to accommodate more than 1,000 people.

The renovation of the Second World War-era Igeldamms shelter in central Stockholm was completed in September, and work on 24 out of 80 other large shelters is continuing.

The entire renovation process, including the upgrade of air filters and replacement of diesel generators, can take up to two to three years, according to the Swedish Civil Contingencies Agency.

The government hopes that the increased funding for the civil defense in the coming years will boost the pace of this process.

But the agency's shelter specialist, Anders Johannesson, says the money allocated to the renovation annually is unlikely to cover the cost of fixing all of Sweden's 64,000 shelters, let alone the building of new ones.

Late last year, the country's civil defense minister warned that the military threat against Sweden had increased and that an armed attack could not be excluded.

He was speaking as he announced another update of a Cold War-era civil emergency advice booklet.

Besides giving practical advice on cyber- and terror attacks, pandemic and environmental threats, along with conventional warfare, it also carries items on self-defense, psychological defense, digital security and protection against air raids.

The first edition of the booklet was published during World War Two.

AP video by Kostya Manenkov